diff --git a/docs/en/docs/tutorial/security/first-steps.md b/docs/en/docs/tutorial/security/first-steps.md
index 1ec31b408ce0f..a769cc0e6deb1 100644
--- a/docs/en/docs/tutorial/security/first-steps.md
+++ b/docs/en/docs/tutorial/security/first-steps.md
@@ -51,6 +51,8 @@ Copy the example in a file `main.py`:
 
     `pip install python-multipart`
 
+    This is because **OAuth2** uses "form data" for sending the `username` and `password`.
+
 Run the example with:
 
 <div class="termy">